Translucent material



Fatented Mar. 20, 1934 51,951,933 TKANSLUCENT MATERIAL Frederick W. Hochstetter, Pittsburgh, Pa;

' No Drawing. Application July 21, 192i, I Serial No. 207,572

3 Claims.

I This invention relates to translucent mediums ing translucent transparent cellulose films,

5 sheets, webs, etc.

object of this invention is.to provide a composition of matter for treating transparent cellulose films, webs, etc. to render themtranslucent and/or sensitized for use as positives'or negatives 10' in photographic or allied arts.

a composition of matter for treating transparent cellulose films, webs, etc. for the purpose of making translucent bases or permanent supports for use as negatives or positives in photographic and allied arts.

'The present photographic negatives when developed and fixed in the well known manner are transparent in the shadows and are semi-opaque in the high lights or half tones and in order to subdue the light in the printing machines it is necessary to use a translucent material such as ground glass for the purpose ofbalancing the exposure. The ground glass or equivalent material retards thespeed of exposure in the shadows of the negatives which are transparent and gives more time for exposure of the high lights and half tones in order that the resulting image will have a better balanced reproduction of gradation recorded in the negative.

I have found in practice that by providing a translucent base support for photographic negatives the use of ground glass or its equivalent in the printing machines may be eliminated and in addition by having the translucent base in contact with the emulsion or sensitized surfaces of the negatives the balance of exposure is considerably better than that obtained by the present method of using ground glass in the printing machine. vis located at a distance from the negative and does not provide as uniform distribution of light as is obtained by using translucent negatives as stated above.

The present films or plates used in the X-ray art are transparent after they have been exposed, developed and fixed and in order to diagnose the images recorded on the negatives'it is a w, from age and handling. Another object of this invention is to produce The ground glass in printing machines webs, etc. in orderto render the same translucent and sensitized for use as positives or negatives in photographic and allied arts and for other useful purposes; a

Ai'urther object of this invention is to provide a. composition of matter for giving to cellulose films, webs, etc. the above characteristics, render them free from brittleness, provide the necessary strength and tenacity, and prevent deterioration These and other objects I attain by means of the method and composition of matter hereinafter described.

In practicing this invention. I prefer to start with transparent sheets, films, webs, etc. of viscose xanthate, the other viscose and aqueous cellulose compounds and their derivatives such as Cellophane. The process of carrying out the method of this invention in connection with such materials may be conveniently done in the manner disclosed in United States Patent No. 1,403,779, issued to me on date of January 17, 1922.

By means of this invention I produce colloidal gel or gelatinous compounds consisting of a plurality of separately compounded mixtures prepared in a predetermined manner and I finally compound together all of the mixtures in a predetermined manner.

For the sake of simplicity the various mixtures will hereinafter be referred to as A, B, C, and D, and the components of these mixtures may be as follows:

Mixture A.

12,000 cc; distilled water. 1360 grams soft gelatine or its equivalent. 60 ccspot'assium bromide, 10% solution. 3,000 cc. potassium chloride, 2% solution. 350 cc. glycerine'.

Mixture B.-.

3,500 cc. distilled water. 550 grams starch. 40 cc. copper chloride, l0% solution.

Mixture C.--

2,000 cc. silver nitrate, 2% solution, or

stronger silver solution if more sensitiveness is desired.

.Mixture D. I a

5 cc. potassium iodide, 2% solution. 30 cc. citric acid, 10% solution. 50 cc. chrome alum, 10% solution. 125 cc. formaldehyde, 28% solution. 250 cc. alcohol. 300cc. soap bark, 10% solution.

In accordance with this invention I preferably compound the components of each mixture in separate vessels and subject the mixtures A, B and D to a temperature of 145 F. for a period of thirty minutes and the mixture C to a temperature of 80 F. for the same period. The mixtures are then permitted to digest for a period of a half hour after which time all of the mixtures are compounded together in one vessel under constant stirring in the following order.

In a dark room, mixture B is added to A, C to AB and finally D to ABC. After the compound has been thoroughly mixed it is further subjected to a temperature of 145-F. for a period of thirty minutes at the end of which time the composition of matter is ready to be applied to one or both sides of a medium by the well known practice used in applying light sensitive compounds or emulsions to such mediums but preferably in accordance with the method of my above mentioned patent.

Transparent aqueous cellulose mediums treated with this composition of matter are adapted for use in photographic and allied arts and may be used for negatives or positives exposed or printed in the usual way, developed in any suitable manner, washed and fixed in acid alum thiosulphate baths. The resulting product will be negatives or positives having a permanent base support resembling ground glass.

If the finished product is desired for use for other purposes than photographic arts such as translucent window panes, motion picture screens for daylight projections or the like, the product is first subjected to the developing process, is Washed and then subjected to the action of a fixing bath without exposing to light for the pur pose of destroying its light sensitive characteristics. The fixing bath may consist of the following components:

5,000 cc. distilled water.

965 grams sodium thiosulphate (hypo).

100 grams of potassium aluminum sulphate. 500 cc. acetic acid.

50 grams sodium sulphite.

After the product has been subjected to such thiosulphate bath it will not be sensitive to light but will have the appearance of ground glass of fine uniform translucent nature.

A finished product having any predetermined flexibility may be had by adding a predetermined amount of glycerine or its equivalent to mixture A. A harder product may be had by adding either chrome alum, formaldehyde or both or their equivalents to the mixtures A, B, C, and D.

In case the composition of matter consisting of the mixtures A, B, C and D becomes hardened too much during the compounding of the mixtures it may be conditioned by adding more acid.

I do not desire to confine this invention to the particular components of the compounds that that these temperatures be exactly adhered to.

It will be obvious that transparent materials other than aqueous cellulose compounds may be treated with this composition of matter and. in the manner described when such materials are first provided with a substratum which renders their surface absorbent to aqueous compounds.

What I claim as new and desire to secure by Letters Patent is:

1. An article of manufacture of the kind described comprising a translucent aqmous cellulose base having integrally combined therewith a light-sensitive translucent emulsion, said emulsion containing the products of reaction of potassium bromide, chloride and iodide, silver nitrate, gelatine, glycerine, starch, copper chloride, citric acid, chrome alum, formaldehyde, alcohol and soap bark, insofar as their afiinities and concentrations make the same possible, there being certain unreacted contents, the whole imparting predetermined physical and photochemical characteristics to the article of manufacture.

2. An article of manufacture of the kind described comprising a translucent aqueous cellulose base having integrally combined therewith a light-sensitive translucent emulsion, said emulion containing the products of reaction of 60 c. c. potassium bromide (10%), 3000 c. c. potassium chloride (2%), 5 c. c. potassium iodide (2%), 2000 c. 0. silver nitrate (2%),1360 grams gelatine, 350 c. c. glycerine, 550 grams starch, 40 c. 0. copper chloride (10%), 30 c. c. citric acid (10%) 50 c. c. chrome alum (10%), 125 c. c. formaldehyde (28%), 250 c. 0. alcohol and 300 c. c. soap bark solution (10%), there being certain unreacted contents, the whole imparting predetermined physical and photochemical characteristics to the article of manufacture.

3. A method of the character described which includes preparing a first mixture of 12,000 0. c. distilled water, 1360 grams gelatine, 60 c. c. potassium bromide (10%), 3000 c. c. potassium chloride (2%) and 350 c. c. glycerine preparing a second mixture of 3500 c. c. distilled water, 550 grams starch, and 40 c. 0. copper chloride (10%) preparing as a third mixture 2000 c. 0. silver nitrate (2%); preparing a fourth mixture of 5 c. c. potassium iodide (2%), 30 c. c. citric acid (10%), 50 c. c. chrome alum (10%), 125 c. 0. formaldehyde (28%), 250 c. c. alcohol and 300 c. c. soap bark solution (10%); subjecting the first, second and fourth mixtures to a temperature of about 145 F. for about thirty minutes, subjecting the third mixture to a temperature of about F. for about thirty minutes, then digesting each mixture for about thirty minutes, combining the mixtures in the absence of acetinic light in the order first named, subjecting the combined mixtures to a temperature of about 145 F. for about thirty minutes and finally applying the same to a transparent aqueous cellulose base to produce a translucent article of manufacture of predetermined physical and photochemical characteristics.

FREDERICK w. HOCHS'I'ETTER. 

